Unregulated Substances
In addition to testing drinking water for contaminants regulated under the Safe Drinking Water Act, we sometimes also monitor for contaminants that are not regulated. Unregulated contaminants do not have legal limits for drinking water.
The following table shows the unregulated contaminants we detected last year, as well as human-health based guidance values for comparison, where available. MDH, EPA and other health agencies may have developed comparison values for some of these compounds. Some of these comparison values are based only on potential health impacts and do not consider our ability to measure contaminants at very low concentrations or the cost and technology of prevention and/or treatment. These values may be set at levels that are costly, challenging, or impossible for water systems to meet (for example, large-scale treatment technology may not exist for a given contaminant). Sample data are listed along with comparison values in the table below; it is important to note that these comparison values are not enforceable.
Detection alone of a regulated or unregulated contaminant should not cause concern. The significance of a detection should be determined considering current health effects information. We are often still learning about the health effects, so this information can change over time.
A person drinking water with a contaminant at or below the comparison value would be at little to no risk for harmful health effects. If the level of a contaminant is above the comparison value, people of a certain age or with special health conditions-like a fetus, infants, children, elderly, and people with impaired immunity—may need to take extra precautions. We are notifying you of the unregulated contaminants we have detected as a public education opportunity. Unregulated substances More information is available on:
MDH’s A-Z List of Contaminants in Water
Fourth Unregulated Contaminant Monitoring Rule (UCMR 4)
Fifth Unregulated Contaminant Monitoring Rule
EPA UCMR 5 Data Finder: The Unregulated Contaminant Monitoring Rule 5 (UCMR5) Data finder allows people to easily search for, summarize, and download the available UCMR 5 analytical results.
EPA has developed a UCMR5 Program Overview Factsheet describing UCMR 5 contaminants and standards.
In the past year, your drinking water may have been tested for additional unregulated contaminants and results are still being processed as part of the Fifth Unregulated Contaminant Monitoring Rule
Unregulated Substances Tested in the Drinking Water
Substance (Units) | Comparison Value | Highest Average Results or Highest Single Test Result | Range of Detected Test Results |
Sodium* | 20 ppm | 26.6 ppm | N/A |
Sulfate | 500 ppm | 21.3 ppm | N/A |
Perfluorobutanesulfonate (PFBS) | 100 ppt | 1 ppt | 0.00 - 2.20 ppt |
Perfluorobutanoic Acid (PFBA) | 7000 ppt | 20.33 ppt | 13.10 - 26.00 ppt |
Perfluoroheptanoic Acid (PFHpA) | N/A | 0.7 ppt | 0.00 -1.50 ppt |
Perfluorohexanesulfonate (PFHxS) | 47 ppt | 0.9 ppt | 0.00 - 1.90 ppt |
Perfluorohexanoic Acid (PFHxA) | 200 ppt | 1.1 ppt | 0.00 - 2.20 ppt |
Perfluorononanoic acid (PFNA) (2023) | N/A | 0.09 ppt | 0.00 - 0.37 ppt |
Perfluoropentanoic Acid (PFPeA) | N/A | 1.99 ppt | 0.00 - 2.90 ppt |
Perfluorooctanoic Acid (PFOA) | 0.0079 ppt | 1.2 ppt | 0.0000 - 2.8000 ppt |
Perfluorooctanesulfonate (PFOS) | 2.3 ppt | 0.8 ppt | 0.00 - 1.80 ppt |
*Note that home water softening can increase the level of sodium in your water.
Note About PFAS
In early 2024, MDH released new comparison values for two PFAS compounds, PFOA and PFOS. MDH is still evaluating how to apply these comparison values to drinking water systems. Additionally, EPA released final MCLs for PFOA at 4.0 ppt, PFOS at 4.0 ppt, PFHxS at 10 ppt, HFPO-DA (Gen X) at 10 ppt, PFNA at 10 ppt, and a calculated Hazard Index at 1 (unitless) that will become enforceable April 26, 2029. Additional Information on PFAS system results is available at: Interactive Dashboard for PFAS Testing in Drinking Water - MN Dept. of Health